Subjunctive with Conjunctions

The verbs to doubt (dudar) and to deny (negar) take the subjunctive when they are affirmative, but not when they are negative.

Spanish Subjunctive with Conjuctions

Examples:

I doubt he'll come.

Dudo que venga.

I don't doubt that he'll come.

No dudo que viene.

Conjunctions of Time

Take the indicative when the action in the subordinate clause is either habitual or in the past. The subjunctive is used when the main clause is a command or in the (potential) future:

English

Spanish

as soon as

así que

when

cuando

after

después de que

as soon as

en cuanto

until

hasta que

as soon as

luego que

as soon as

tan pronto como

Examples:

I worked until my kids called.

Trabajé hasta que mis niños me llamaron.

I (usually) work until my kids call.

Trabajo hasta que mis niños me llaman.

Others Conjunctions Which Require The Subjunctive

The Spanish subjunctive is required after a number of common conjugations and relative pronouns, whereas its usage is optional after others.

English

Spanish

on the condition that

a condición de que

so that

a fin de que

unless

a menos que

before

antes (de) que

provided that

con tal (de) que

The Spanish subjunctive is an important item in Spanish grammar and also is used for other language as Portuguese for this, if you can learn other language, you should learn Portuguese grammar that are will more easy for you.